Buggy code:
public class CommandLineClient extends Client { private static final Logger logger = Logger . getLogger ( CommandLineClient . class . getSimpleName ( ) ) ; private static final String SERVER_SCHEMA = "https:////" ; private static final String SERVER_HOSTNAME = "127.0.0.1" ; private static final String SERVER_REST_API = WebServer . API_ENDPOINT_REST_XML ; private static final String LOG_FILE_PATTERN = "syncany.log" ; private static final int LOG_FILE_COUNT = 4 ; private static final int LOG_FILE_LIMIT = 25000000 ; private static final String HELP_TEXT_RESOURCE_ROOT = ( "//" + ( CommandLineClient . class . getPackage ( ) . getName ( ) . replace ( "." , "//" ) ) ) + "//" ; private static final String HELP_TEXT_HELP_SKEL_RESOURCE = "cmd//help.skel" ; private static final String HELP_TEXT_VERSION_SHORT_SKEL_RESOURCE = "incl//version_short.skel" ; private static final String HELP_TEXT_VERSION_FULL_SKEL_RESOURCE = "incl//version_full.skel" ; private static final String HELP_TEXT_USAGE_SKEL_RESOURCE = "incl//usage.skel" ; private static final String HELP_TEXT_CMD_SKEL_RESOURCE = "cmd//help.%s.skel" ; private static final String MAN_PAGE_MAIN = "sy" ; private static final String MAN_PAGE_COMMAND_FORMAT = "sy-%s" ; private String [ ] args ; private File localDir ; private PrintStream out ; public CommandLineClient ( String [ ] args ) { } public void setOut ( OutputStream out ) { } public int start ( ) throws Exception { try { OptionParser parser = new OptionParser ( ) ; parser . allowsUnrecognizedOptions ( ) ; OptionSpec < Void > optionHelp = parser . acceptsAll ( Arrays . asList ( "h" , "help" ) ) ; OptionSpec < File > optionLocalDir = parser . acceptsAll ( Arrays . asList ( "l" , "localdir" ) ) . withRequiredArg ( ) . ofType ( File . class ) ; OptionSpec < String > optionLog = parser . acceptsAll ( Arrays . asList ( "log" ) ) . withRequiredArg ( ) ; OptionSpec < Void > optionLogPrint = parser . acceptsAll ( Arrays . asList ( "print" ) ) ; OptionSpec < String > optionLogLevel = parser . acceptsAll ( Arrays . asList ( "loglevel" ) ) . withOptionalArg ( ) ; <START_BUG> OptionSpec < Void > optionDebug = parser . acceptsAll ( Arrays . asList ( "D" , "debug" ) ) ; <END_BUG> OptionSpec < Void > optionShortVersion = parser . acceptsAll ( Arrays . asList ( "v" ) ) ; OptionSpec < Void > optionFullVersion = parser . acceptsAll ( Arrays . asList ( "vv" ) ) ; OptionSet options = parser . parse ( args ) ; List < ? > nonOptions = options . nonOptionArguments ( ) ; int versionOptionsCode = initVersionOptions ( options , optionShortVersion , optionFullVersion ) ; if ( versionOptionsCode != ( - 1 ) ) { return versionOptionsCode ; } int helpOrUsageCode = initHelpOrUsage ( options , nonOptions , optionHelp ) ; if ( helpOrUsageCode != ( - 1 ) ) { return helpOrUsageCode ; } List < Object > nonOptionsCopy = new ArrayList < Object > ( nonOptions ) ; String commandName = ( ( String ) ( nonOptionsCopy . remove ( 0 ) ) ) ; String [ ] commandArgs = nonOptionsCopy . toArray ( new String [ 0 ] ) ; Command command = CommandFactory . getInstance ( commandName ) ; if ( command == null ) { return showErrorAndExit ( ( "Given<seq2seq4repair_space>command<seq2seq4repair_space>is<seq2seq4repair_space>unknown:<seq2seq4repair_space>" + commandName ) ) ; } if ( options . has ( optionHelp ) ) { return showCommandHelpAndExit ( commandName ) ; } initLocalDir ( options , optionLocalDir ) ; int configInitCode = initConfigIfRequired ( command . getRequiredCommandScope ( ) , localDir ) ; if ( configInitCode != 0 ) { return configInitCode ; } initLogOption ( options , optionLog , optionLogLevel , optionLogPrint , optionDebug ) ; return runCommand ( command , commandName , commandArgs ) ; } catch ( Exception e ) { CommandLineClient . logger . log ( Level . SEVERE , "Exception<seq2seq4repair_space>while<seq2seq4repair_space>initializing<seq2seq4repair_space>or<seq2seq4repair_space>running<seq2seq4repair_space>command." , e ) ; return showErrorAndExit ( e . getMessage ( ) ) ; } } private int initVersionOptions ( OptionSet options , OptionSpec < Void > optionShortVersion , OptionSpec < Void > optionFullVersion ) throws IOException { } private int initHelpOrUsage ( OptionSet options , List < ? > nonOptions , OptionSpec < Void > optionHelp ) throws IOException { } private void initLocalDir ( OptionSet options , OptionSpec < File > optionLocalDir ) throws Exception , ConfigException { } private int initConfigIfRequired ( CommandScope requiredCommandScope , File localDir ) throws ConfigException { } private void initLogOption ( OptionSet options , OptionSpec < String > optionLog , OptionSpec < String > optionLogLevel , OptionSpec < Void > optionLogPrint , OptionSpec < Void > optionDebug ) throws IOException , SecurityException { } private void initLogLevel ( OptionSet options , OptionSpec < Void > optionDebug , OptionSpec < String > optionLogLevel ) { } private void initLogHandlers ( OptionSet options , OptionSpec < String > optionLog , OptionSpec < Void > optionLogPrint , OptionSpec < Void > optionDebug ) throws IOException , SecurityException { } private int runCommand ( Command command , String commandName , String [ ] commandArgs ) { } private int runLocally ( Command command , String [ ] commandArgs ) { } private int sendToRest ( Command command , String commandName , String [ ] commandArgs , File portFile ) { } private int handleRestResponse ( Command command , HttpResponse httpResponse ) throws Exception { } private Request buildFolderRequestFromCommand ( Command command , String commandName , String [ ] commandArgs , String root ) throws Exception { } private PortTO readPortConfig ( File portFile ) { } private int showShortVersionAndExit ( ) throws IOException { } private int showFullVersionAndExit ( ) throws IOException { } private int showUsageAndExit ( ) throws IOException { } private int showHelpAndExit ( ) throws IOException { } private int showCommandHelpAndExit ( String commandName ) throws IOException { } private int execManPageAndExit ( String manPage ) { } private int printHelpTextAndExit ( String helpTextResource ) throws IOException { } private String replaceVariables ( String line ) throws IOException { } private int showErrorAndExit ( String errorMessage ) { } }

Fix:
OptionSpec < Void > optionDebug = parser . acceptsAll ( Arrays . asList ( "d" , "debug" ) ) ;